This invention relates generally to wireless communications circuitry, and more particularly, to calibrating wireless communications circuitry.
Handheld electronic devices and other portable electronic devices are becoming increasingly popular. Examples of handheld devices include handheld computers, cellular telephones, media players, and hybrid devices that include the functionality of multiple devices of this type. Popular portable electronic devices that are somewhat larger than traditional handheld electronic devices include laptop computers and tablet computers.
Due in part to their mobile nature, portable electronic devices are often provided with wireless communications capabilities. For example, handheld electronic devices may use long-range wireless communications to communicate with wireless base stations. Cellular telephones and other devices with cellular capabilities may communicate using cellular telephone bands. Electronic devices may also use short-range wireless communications links. For example, portable electronic devices may communicate using the Wi-Fi® (IEEE 802.11) bands at 2.4 GHz and 5.0 GHz and the Bluetooth® band at 2.4 GHz. Communications are also possible in data service bands such as the 3G data communications band at 2170 MHz (commonly referred to as UMTS or Universal Mobile Telecommunications System band).
Proper operation of the wireless circuitry in an electronic device typically requires calibration. When operated with default settings, electronic devices may, for example, produce radio-frequency output power levels that differ somewhat from expected levels. If these discrepancies are too large in a device, the device may not operate as intended. For example, the device might not transmit signals with sufficient strength during operation, leading to dropped calls or other disruptions in wireless service.
With conventional calibration techniques, amplifier bias voltages and other settings in a device are adjusted while measuring resulting output power levels. Measurement results are then processed in an attempt to estimate properly calibrated values for the settings. Traditionally, there is a complex interplay between the different settings used to operate a device, so the process of making measurements and estimating calibration values may not always be sufficiently accurate.
It would therefore be desirable to be able to improve calibration techniques for wireless devices such as portable electronic devices.